1. Field of the Invention
The present invention relates generally to the field of wireless communications, and particularly to the design of an antenna.
2. Background
Small antennas are required for portable wireless communications. With classical antenna structures, a certain physical volume is required to produce a resonant antenna structure at a particular radio frequency and with a particular bandwidth. A fairly large volume is required if a large bandwidth is desired. Accordingly, the present invention addresses the needs of small compact antenna with wide bandwidth.
The present invention provides a multiresonant antenna structure in which the various resonant modes share at least portions of the structure volume. The frequencies of the resonant modes are placed close enough to achieve the desired overall bandwidth. Various embodiments are disclosed. The basic antenna element comprises a ground plane; a first conductor extending longitudinally parallel to the ground plane having a first end electrically connected to the ground plane and a second end; a second conductor extending longitudinally parallel to the ground plane having a first end electrically connected to the ground plane and a second end spaced apart from the second end of the first conductor; and an antenna feed coupled to the first conductor. Additional elements are coupled to the basic element, such as by stacking, nesting or juxtaposition in an array. In this way, individual antenna structures share common elements and volumes, thereby increasing the ratio of relative bandwidth to volume.